128 Agricultural (Jhemistry. 



The first evidence of fermentation is the odor of ammonia. 

 This is noticeable in the barn, especially if it has been closed 

 during the night. It is due to the rapid decomposition of urea, 

 the principal nitrogenous body of the urine. Ammonia contains 

 nitrogen and when its presence is noticed, it is evident that nitro- 

 gen is escaping into the air. It is impossible to entirely prevent 

 the formation of ammonia from the urea, but it is possible to 

 greatly reduce its loss by providing plenty of absorbing material 

 and keeping the manure moist. 



The fermentation of manure is due to different kinds of bac- 

 teria. Some of these can exist only in the presence of air an 

 are called " aerobic," while others do not require free air an 

 are classified as i( anaerobic. " The aerobic organisms are 

 sponsible for the hot fermentation w r hich is the cause of gre 

 loss of value in manure. It is well known that when manure 

 thrown into loose heaps and contains a large proportion of ho 

 or sheep excrement it soon becomes very hot and dry, in fact, h 

 enough to steam, and the temperature may reach 175 Fah 

 In this condition the common "fire fanging," or burning whi 

 in spots, takes place, and heavy losses of nitrogen are sure to 

 cur. Experiments have shown losses of from 30 to 80 per ce 

 of the nitrogen. In extreme cases of fire-fanging all the nitro 

 will be lost. 



If the manure heap is so compact that the air cannot penetra 

 it, the aerobic bacteria are unable to live, and hence hot f ermen 

 tion is prevented. Where aerobic bacteria are active the solubl 

 forms of nitrogen in the manure are partly converted into ni 

 rates and these in turn may be attacked by certain anaerobi 

 bacteria called " denitrifiers, " which liberate elemental or f 

 nitrogen from such compounds. This is an additional reason fo 

 checking, so far as possible, all aerobic fermentations. The pres 

 ence of large quantities of water in the manure heap holds t 

 temperature down, displaces the air and in this way chec 

 aerobic fermentations. For this reason, the moist cow and pi 

 excrements are not so subject to hot fermentation as that of t 



